D A T A S H E E T
COMMAND DEFINITIONS
Writing specific address and data commands or se-
quences into the command register initiates device op-
erations. Table 5 defines the valid register command
sequences. Writing incorrect address and data val-
ues or writing them in the improper sequence may
place the device in an unknown state. A reset com-
mand is then required to return the device to reading
array data.
however, the device ignores reset commands until the
operation is complete.
The reset command may be written between the se-
quence cycles in an autoselect command sequence.
Once in the autoselect mode, the reset command
must be written to return to reading array data (also
applies to autoselect during Erase Suspend).
If DQ5 goes high during a program or erase operation,
writing the reset command returns the device to read-
ing array data (also applies during Erase Suspend).
All addresses are latched on the falling edge of WE#
or CE#, whichever happens later. All data is latched on
the rising edge of WE# or CE#, whichever happens
first. Refer to the appropriate timing diagrams in the
“AC Characteristics” section.
Autoselect Command Sequence
The autoselect command sequence allows the host
system to access the manufacturer and devices
codes, and determine whether or not a sector is pro-
tected. Table 5 shows the address and data require-
ments. This method is an alternative to that shown in
Table 4, which is intended for PROM programmers
and requires VID on address bit A9.
Reading Array Data
The device is automatically set to reading array data
after device power-up. No commands are required to
retrieve data. The device is also ready to read array
data after completing an Embedded Program or Em-
bedded Erase algorithm.
The autoselect command sequence is initiated by writ-
ing two unlock cycles, followed by the autoselect com-
mand. The device then enters the autoselect mode,
and the system may read at any address any number
of times, without initiating another command se-
quence. A read cycle at address XX00h retrieves the
manufacturer code. A read cycle at address XX01h in
word mode (or 02h in byte mode) returns the device
code. A read cycle containing a sector address (SA)
and the address 02h in word mode (or 04h in byte
mode) returns 01h if that sector is protected, or 00h if
it is unprotected. Refer to Tables 2 and 3 for valid sec-
tor addresses.
After the device accepts an Erase Suspend command,
the device enters the Erase Suspend mode. The sys-
tem can read array data using the standard read tim-
ings, except that if it reads at an address within
erase-suspended sectors, the device outputs status
data. After completing a programming operation in the
Erase Suspend mode, the system may once again
read array data with the same exception. See “Erase
Suspend/Erase Resume Commands” for more infor-
mation on this mode.
The system must issue the reset command to re-en-
able the device for reading array data if DQ5 goes
high, or while in the autoselect mode. See the “Reset
Command” section, next.
The system must write the reset command to exit the
autoselect mode and return to reading array data.
See also “Requirements for Reading Array Data” in
the “Device Bus Operations” section for more informa-
tion. The Read Operations table provides the read pa-
rameters, and Figure 13 shows the timing diagram.
Word/Byte Program Command Sequence
The system may program the device by word or byte,
depending on the state of the BYTE# pin. Program-
ming is a four-bus-cycle operation. The program com-
mand sequence is initiated by writing two unlock write
cycles, followed by the program set-up command. The
program address and data are written next, which in
turn initiate the Embedded Program algorithm. The
system is not required to provide further controls or
timings. The device automatically generates the pro-
gram pulses and verifies the programmed cell margin.
Table 5 shows the address and data requirements for
the byte program command sequence.
Reset Command
Writing the reset command to the device resets the
device to reading array data. Address bits are don’t
care for this command.
The reset command may be written between the se-
quence cycles in an erase command sequence before
erasing begins. This resets the device to reading array
data. Once erasure begins, however, the device ig-
nores reset commands until the operation is complete.
When the Embedded Program algorithm is complete,
the device then returns to reading array data and ad-
dresses are no longer latched. The system can deter-
mine the status of the program operation by using
The reset command may be written between the se-
quence cycles in a program command sequence be-
fore programming begins. This resets the device to
reading array data (also applies to programming in
Erase Suspend mode). Once programming begins,
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